U.S. Pat. No. 4,265,076 to Krutz describes a machine that macerates forage with two serrated rolls and forms a continuous mat with two compression rolls. The residence time of forage between two rolls during maceration and two other rolls during compression is relatively short, and makes it difficult to obtain very severe conditioning and a uniform mat. Moreover, there is no provision to recuperate juice when it flows out from very wet forage at the compression stage.
U.S. Pat. No. 4,332,125 to Holdren describes a machine that makes discontinuous mats of macerated forage. The main problem with this design is that it accumulates forage on a compression belt until enough material is prepared in a rectangular mat. Under modern operating conditions of high yield and high feed rate, it appears preferable to deposit the macerated forage rapidly and continuously to avoid any plugging.
U.S. Pat. No. 5,036,652 to Schmittbetz and Liebers describes a machine that macerates forage between multiple planetary grooved rolls and compresses the mat between two rolls. The main difference between this machine and the above mentioned Krutz patent is the macerating roll configuration.
Savoie and coworkers (1991, ASAE paper 91-1578, St. Joseph, Mich.; 1993, Transactions of the ASAE 36(2):285-291) describe an experimental unit with a 2.1 m wide cutter bar, eight 1.5 m wide macerating rolls and a 1.2 m wide double-belt press. Maceration was adequate but the machine was bulky and complex. The two rubber belts were subject to high lateral forces under variable yield and moisture and sometimes deposited thick clumps of forage instead of a uniformly thin mat.
Technical report no 13.93 dated June 1993 from Deutz Fahr Company (Kodelstrasse 1, Lauingen, Germany, D89415) describes a 2.8 m wide disk mower, 8-roll maceration system and 8-roll compression unit with additional intermediate components (eight rolls and two belts) to even out material flow. Such a machine is not likely to handle large feed rates which would cause plugging in the intermediate components.
U.S. Pat. No. 5,152,127 to Koegel and co-workers describes a machine that mows and macerates forage by impact. The machine requires upward acceleration of the mowed forage to reach the impact roll. This may limit the use of impact roll maceration to flail mowers.
Commercial literature dated January 1994 from Krone Company (P.O. Box 1163, Spelle, Germany, D-48478) describes a machine with a hammer roll for intensive forage conditioning. However, the hammer roll conditioning machine is a separate unit that picks up an already mowed swath and is therefore not integrated with a mower. The machine does not have any provision for forming compressed mats.
While there have been several attempts to improve forage drying with intensive conditioning, none has successfully handled large feed rates and produced well-formed macerated continuous swaths or mats. It is also important that the intensive conditioning system be integrated in a single machine that includes a mowing mechanism.